Wow, you've got your work cut out for you... but hey, congratulations! I'm terribly allergic to dogs, and even worse with cats... but so long as we keep our lil' boy in a short puppy cut, I don't have any problems at all with allergies with him.
First off, we are portable crate people too. I don't think it's caused us any harm - the crate goes in the room we are in. We'd probably prefer buying a crate for every room so we don't have to lug it around, but hey - I'd rather buy him a couple new toys or a higher quality kibble instead of multiple crates.
Don't worry too much about him being a mellow puppy right now. Our boy Nikko is getting close to 6mo old, and still every day now he shows us a new side of his wild personality. Some new thing he decides is fun, or just as an example this past week he discovered the joys of digging, lol. Just wait - he will get TONS of personality and energy you never before thought was possible out of your calm happy docile little puppy.
One of the things you could look into as far as feeding goes is Prey Model Raw, especially if you don't trust any locally available brands of kibble... we are looking into starting to give Nikko some (or all) of of this in the near future. A good thread to check out for info on this type of food is
HERE.
Definitely get him a designated potty area, and preferably a door that is designated for potty-time only so he can learn how to tell you when he has to pee (and doesn't get that confused with when he wants to play or go for a walk). Read up here on YorkieTalk about potty training... it's no easy task with these super-smart independent little buggars. Some people luck out, but most of us go through heck getting our little ones potty trained!
Have fun!
Lauren & Nikko